One day a man is out driving with his son. The two are involved in a terrible car accident. The man is killed instantly. The son, horribly injured, is rushed to the nearest hospital where, as luck would have it, the greatest trauma surgeon of the age is working.

The lad is rushed in on a gurney and the surgeon looks him over. “I can’t treat this boy!” The surgeon cries, “This is my son.”

Now, quickly: What has just happened?

The answer is at the bottom of the page. But, before you scroll down to find it—unless you already know—take a moment to let your mind construct scenarios that make the story make sense. I’ll wait. Go back and re-read it if you need to.

Assumptions are the things we don’t know we are making.

Got the answer? We used to think that if we wanted to study a species we could just study the males and assume that the females pretty much approximated to this. Well, they don’t--and the reason isn’t hard to find.

If males were the same as females then females would not have created them. It’s that simple. If you want to maximize the number of your genes into the next generation then why halve the chance by sharing them out with another organism unless there is good reason to do so?

And, if you don’t want to maximize the number of your genes in the next generation, then you will be shoved aside by something that does.

No sex please--we're bdelloid rotifers

Yet, every complex organism—or eukaryote—bar one, uses sexual reproduction. Each parent contributes half the genes—give or take. Since females arrived on the scene first then it follows that they created males. And, in the case of bdelloid rotifers (above) uncreated them again.

Close inspection reveals this diorama to be a replica of the village of Bourton-on-the-Water itself. Nerd that I am, I immediately rushed to look at the model version of the Old New Inn pub to see if there was a model of the model in that, and was delighted to find that there was.

Little fleas have lesser fleas...

Was there also a model of the model of the model? Alas, no—that’s where it ended.

The same principle applies to brains. Brains exist to do at least this—generate predictions about the future. They often do this by building internal models. As the Bourton-on-the-Water example shows, any sophisticated model will have to contain a model of itself as well. Our brains are at least this sophisticated.

In humans this model of the model is called the somatosensory cortex. Pictures of it are sometimes called a Penfield Homunculus after the pioneering neuro-surgeon Wilder Penfield. He was the first to discover that you could open up obliging peoples’ brains and play their bodies like a sophisticated piano if you knew which keys to press.

Assumptions are the things we don’t know we are making. For years it was simply assumed that the female somatosensory cortex was like the males. But it isn’t. And, why should it be? It runs a very different system. Gillian Einstein, recently publicised by Anne Fausto-Sterling, has rather wittily termed this the Hermunculus and has argued forcefully that it’s time for neglect of direct study of female sexual anatomy to be turned around*.

So, what about Good Housekeeping and the sex toy review? Humans, in common with various other animals, don’t just have sex when they reproduce. They can have preferentially homosexual sex, sex when not fertile, even sex when well beyond the age for fertility. While the ultimate function of any trait is cashed out in terms of genetic representation this does not mean that every single act that looks like sex has to lead directly to reproduction. Sex can express feelings, bind people together, or just be for fun.

And the Winner is…

Is the rabbit sold separately?

As I have blogged before—females now generate a market place where they can express preferences. When they do there is an interesting artificial selection that is set up that in some ways allows us to view an external model of what is going on inside. And sometimes what is going on inside females is a desire for swift, efficient release of sexual tension. Rabbits have already figured prominently in the female sex toy universe. Now it's the turn of the love egg—and its recent incarnation the Je Joue Mimi. Winner of the Good House-Keeping sex-toy review.

Happy Easter

*In an earlier draft I wrongly attributed the first coining of the term "hermunculus" to Anne Fausto-Sterling. Proper scholar that she is, she was quick to tell me that the first coinage of "Hermunculus" is actually due to the Canadian Psychologist Gillian Einstein. Oops! Di Noto, P. M., Newman, L., Wall, S., & Einstein, G. (2013). The hermunculus: what is known about the representation of the female body in the brain?. Cerebral Cortex, 23(5), 1005-1013. Einstein, G. (2008). From body to brain: considering the neurobiological effects of female genital cutting. Perspectives in biology and medicine, 51(1), 84-97.

The surgeon is a woman, of course! Are you a filthy sexist pig for not immediately realizing this? Probably not. You just have a mental schema that pictures male trauma surgeons as a default. Or, you are proper smarty-pants! When I have used this schema in class I have had offerings like “he was adopted”; “he has gay dads” (which would work, in fact—but it’s interesting that this often gets picked over the more statistically likely scenario); "he’s not really human" (!).

"Since females arrived on the scene first then it follows that they created males."

Sexual reproduction is the combination of two haploid cells. If these cells are the same size - isogamous - then there is neither female nor male. We only get female and male gametes when we get gametes of different sizes - anisogamy. And these were most likely originally within the same hermaphroditic body ie a body that is neither male nor female, or both male and female if you like.